This invention relates generally to cylinder locks, and more particularly to a programmable cylinder lock that allows for adapting the lock to operate upon insertion of a key having a different configuration than a key to which the lock was originally configured for operation.
In many organizations, such as businesses, apartment buildings, hotels, schools, etc., it is generally desirable to customize the locks to the particular organization. There are two general methods by which keys and locks may be customized. The first involves reconfiguring the drivers and tumblers in the lock so that a key with a particular top edge contour may operate the locks of the organization. The second involves configuring the keyways in the locks to accept keys having a unique pattern of longitudinal contours formed in their sides. The purpose of the exclusivity generated by these methods is to prevent unauthorized entry into the organization. When keys and locks formed by the second method are involved, it is not sufficient for opening the lock that one have a key having a top edge contour appropriate to the lock; the key must also include an appropriate longitudinal contour of grooves and/or ridges.
In general, standard, conventional locks include a housing that has a cylindrical bore therein. An elongated generally cylindrical plug is rotatably mounted within the bore. A plurality of cylindrical apertures or holes extend through the housing and can be aligned with corresponding cylindrical holes in the plug. Paired sets of drivers and tumblers are positioned within these holes (i.e., the drivers within the holes in the housing, the tumblers within the holes in the plug) and are capable of moving within the plug and housing in such a manner as to allow for rotational movement of the plug in response to a main key inserted in the lock. The arrangement and construction of the lock also causes one or more of these sets of drivers or tumblers to be positioned in the interface between the plug and housing to prevent relative rotation between the plug and the housing when the wrong main key or no main key is inserted in the lock. However, the relative positioning of the sets of drivers and tumblers, plug, and housing is such that, when the proper key is inserted, the drivers are substantially wholly within the holes in the housing and the tumblers are substantially wholly within the holes in the plug, such that the plug can be rotated without interference to an unlocking position.
Many locks or sets of locks also include two types of keys: tenant or user keys and master keys. In general, each tenant key will only open one lock of a particular subset of locks, whereas a master key may open all the locks of the subset. Over the course of time, the security of an organization may become compromised by the loss of control of one or more of the tenant keys. For example, in apartment buildings, hotels, or motels, a guest or renter may leave and inadvertently or intentionally retain a key. When this occurs, subsequent occupants or tenants cannot be secure in their persons and property. Thus it would be desirable to easily and quickly reprogram the locks to accept a new key or set of keys.
Locks that can be easily changed are also desired by businesses where several employees are in possession of keys to fit the locks. In such situations, an employee may be discharged or quit, but retain possession of a key. Further, an employee may lose a key, thus placing the security of the locked area in doubt. Locks that can be easily changed are also desired in matters of personal security. One example of such a situation is a school where teachers and/or administrators may wish to quickly change the configuration of locks on classroom doors to secure students inside the classroom and safely set apart from the hallways in the event that an undesirable or dangerous individual breaches the security of the school.
Locks that can be easily changed are also desired by homeowners when a member of the family has misplaced or lost the operative user key, or when the family desires to allow limited access to the house through a temporary reconfiguration of a lock to the house. When keys are lost or are possessed adversely, the general response is to change the locks fitting the lost key to require a key with a new top edge contour to correspond to different length tumblers. Generally, the shape of the longitudinal inner walls of the keyway that confront the longitudinal contour on the side of the key is not changed due to the generally exorbitant cost of such a change.
In many conventional locks, rotation of the user or master key with the lock is only permitted in one direction. Generally, such unidirectional locks are manually latched to the closed position, without manipulation of the user key, and are opened or the latch unlocked by insertion and rotation of the operable user key within the lock. Examples of such locks and latches combinations include padlocks, certain deadbolt locks, and knob locks having a push-button locking or latching button on the inside knob. These locks are all characterized as permitting only unidirectional rotation of the lock cylinder or plug within the housing of the lock with an inserted user key.
There are several generally known methods in the prior art for changing the configuration of drivers and tumblers in standard cylinder locks. Some of these methods involve removing the drivers and tumblers from a lock and replacing them with a different set of drivers and tumblers. However, there are many disadvantages to these prior methods of changing locks. First, these methods are tedious and time consuming. Second, they generally require the presence of a locksmith. And finally, they require disassembly and reassembly of the actual lock structure along with removal and replacement of the lock in a door.
Thus, it would be desirable to provide and construct a lock, and particularly a lock permitting only unidirectional rotation with a user key, that permits rapid programming of the lock to a different design or configuration to operate with a different user key. It would further be desirable to provide a lock that allows the operative key to be changed without removal of the plug from the lock, and/or other disassembly of the lock structure. It would be further desirable to provide a lock wherein the user key can not be used to program or change the configuration of the lock.